Various facilities routinely include tanks for storing liquid and gas products. For example, storage tanks are routinely used in tank farms and oil, gas, and chemical storage facilities to store liquid and gas products. As another example, oil tankers and other liquid transport vessels routinely include numerous tanks storing oil or other products.
Often times, it is necessary or desirable to measure the level of a product in a tank, such as during loading of a product into the tank or unloading of a product from the tank. For example, an overfill protection system is typically used to detect when a product is approaching the maximum safe fill level of a tank. Ideally, these measurements are used to stop the filling of the tank before the tank overflows or is damaged and the product escapes from the tank. Overfill protection systems often require extreme reliability and precise measurements of the product in a storage tank.
Among other approaches, radar gauges and servo gauges have been used to measure the product level in a tank. A radar gauge typically transmits radar signals towards a product in a tank and receives radar signals reflected off the surface of the product in the tank. Analysis of the reflected signals can be used to determine the product level in the tank. A servo gauge typically raises and lowers a displacer that sinks in the product within a tank. The servo gauge can determine the product level in the tank based on changes in the displacer's apparent weight, which changes depending on (among other things) whether the displacer is hanging in the air or submerged in the product.